Multiplex communications – Wide area network – Packet switching
Patent
1980-08-21
1983-08-09
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
370 38, H04B 156
Patent
active
043982832
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a superhigh-frequency telecommunications device operating in the duplex mode.
The problem of microwave telecommunications is currently coming up against frequency congestion. The recourse to superhigh frequencies SHF (above 10 GHz) makes it possible to place a large number of telecommunications systems in a limited geographic space due to the use of highly directional antennas. It also permits, at equal passbands, a larger number of systems to be placed in one frequency band, or the use of systems with a large passband.
As propagation is virtually optical, one can use highly directional antennas having small dimensions at these frequencies. The large gain of directional antennas only permits the use of very low SHF power. One thus considerably limits the congestion of the ether. Finally, these very high frequencies permit the use of broad modulation spectra (telephony, multiplex, data transmission, video transmission, etc.).
Such a duplex superhigh-frequency telecommunications device would permit the connection, to an existing telephone network, of subscribers for which it is impossible or too costly to install a telephone line. This device would also permit the interconnection of two fixed points, in line-of-sight, to allow the transmission of all types of information which could not be carried by a standard telephone line.
However, such a duplex superhigh-frequency telecommunications device, as it can exist at present, has the disadvantage of being very expensive, especially with superhigh frequency, because it should comprise, for full duplex realization, at each end: a transmitter, a receiver, two antennas or one antenna with a decoupling system. On the other hand, it uses two carrier frequencies to realize the duplex, with the protection necessary for filtering one frequency in relation to the other.
The invention is designed to avoid the disadvantages of known devices by using equipment that is very simple and not very cumbersome. It concerns a superhigh-frequency telecommunications device operating in the duplex mode of the type comprising, for each station, a superhigh-frequency oscillator which delivers a carrier to an antenna and a quench oscillator which delivers a carrier quench signal, characterized in that the quench oscillator at each station delivers a specific frequency signal, and is frequency-modulated by the information to be transmitted so that the carrier quench signal is used as a subcarrier of the information to be transmitted; and in that each station comprises a selective filter tuned to the frequency of the quench signal of the other station and a frequency modulation detector capable of restoring the information transmitted.
According to another characteristic of the invention, each station operates in superregeneration and assures both transmission and reception with the same antenna.
Other characteristics of the invention result from the description which follows, made with reference to the attached diagram in which one can see:
FIG. 1: a simplified schematic diagram of a known superregenerative device.
FIG. 2: a representation of the shape of the signals delivered by the device in FIG. 1.
FIG. 3: a simplified schematic diagram of a model design of a telecommunications device according to the invention.
FIG. 4: a simplified schematic diagram of a model design of a telecommunications device according to the invention using a heterodyne oscillator for reception.
FIG. 5: a simplified schematic diagram of a model design of a station for a telecommunications device according to the invention capable of assuring the restoration of conventional telephone signals.
FIG. 6: a representation of the shape of the signals and an example of the ratio of SHF pulse length.
The invention described here permits considerable simplification of the duplex superhigh-frequency telecommunications device. It also permits the use of only one SHF carrier frequency to realize the duplex link in both directions, and this without altering the possibilities of transmitting various info
REFERENCES:
patent: 2273097 (1942-02-01), Foster et al.
patent: 2333719 (1943-11-01), Herold
patent: 2577781 (1951-12-01), Loughlin
patent: 3112445 (1963-11-01), Holden et al.
patent: 3794757 (1974-02-01), Knabe
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